Process of manufacturing crepes with threads of cellulose acetate artificial silk



Patented Apr. 18,- 1933 UNITED STATES PATENT OFFICE CLAUDE CLEHENCON, OF CALUIBE-Ofi-THE-RHONE, FRANCE.

PROCESS IF MANUFACTURING CREPES WITH OF CELLULOSE ACETATE ARTIFICIAL SILK.

llo Drawing. Application fled larch 11, 1982, Serial No. 598,308, and in France. March 16, 1981.

The present invention has for its object a process of manufacturing crepes with threads of cellulose acetate artificial silk.

The fabrics with crepe efi'e'ct are obtained by the employment of highly twisted threads (2000 to 3000 turns'per metre or more or less, in accordance with the material employed and its titre). These threads are generally provided naturally or artificially with a gum or glue which opposes their untwisting in the course of the operations that they have to undergo up to and including the weaving. The may be employed in the warp or in the we separately or together. The fabric obtained is then subjected to a washing operation intended to remove the gum or glue which fixes the twist; inthe course of this washing operation, the fabric undergoes a shrinkage in the direction of the hard twisted threads, which is accentuated by the fact that the fibre swells in the washing bath. When the fabric is dry, it presents the characteristic crepe appearance.

In order to obtain this appearance a certain amount of twist is thereforenecessary which is variable with'the properties of the material employed. According to the present invention, it has been found that the twist to be applied to threads of cellulose acetate, in order to obtain crepe, must be greater than that which is applied to threads of viscose. The example, if 2000 turns per metre.

are suflicient for a thread of viscose with a titre of 100 deniers, 2900 to 3000 turns per metre will be necessary for a thread of cellulose acetate of the same titre in order to have a real crepe after the usual treatments called scouring.

Now, if it is endeavoured to give such 40 twists to such a thread of celluloseacetatc,

the following results are obtained:

1. Numerous elementary fibres and often the whole of the fibres-i. e., the whole threadbreak.

2. The excess of twisting produces small kinks, points at which the torsion .couple has not been exerted around the axis of the thread, but around another difi'erent axis.

3. The resistance-to breaking is considerably reduced (it falls to one third of its'so original value and frequently even lower).

4. The breaking elongation is similarly greatly diminished.

A thread having such properties is unusable and as,'moreover, such a result could only have been arrived at by permanently elongating the thread, the effect of crepe. is not obtained. It is'only possible in practice to give a thread of cellulose acetate with a titre of 100 deniers a twist of 2000 to 2200 0 turns per metre, which is insuificient for obtaining by the usual washing treatments called scouring the creping of a fabric consisting of these threads.

It has been attempted to obtain the crepe effect by the action of swelling liquids on the fabric. There is obtained in this way a shrinkage comparable with that which is obtained by the mercerization of cotton and not with that of the creping of silk. In fact, in 7 I the case of a war of cellulose acetate which has not been hard twisted, the latter shrinks more than the weft and, by drawing the fabric together, opposes the crepe effect. As a matter of fact, the fabric obtained in this 7 Way does not possess the appearance, the feel, the firmness or the elasticity of a crepe. According to the present invention, it has been found that it was possible to give the threads of cellulose acetate much greater twists when they were subjected to a preliminary treatment which consisted inaphysical modification of the thread of cellulose acetate which left its chemical and..tinctorial properties unchanged. This physical modification results from the action of an agent for swelling the cellulose acetate, with or without the addition of a colloid adapted on drying to leave an elastic coating on the thread. The swelling-of the cellulose aceer than those obtained with water, causes a permanent physical modification of the fibre. This modification is preserved after the swelling agent has been removed either by drying, if it is sufficiently volatile, or by suitable washings with water or any other suitable liquid, the washings being followed by drying. The thread has then undergone an internal physical modification the most apparent manifestation of which is a shrinkage (diminution in its length) and which is also characterized by the increase in its breakin elongation and by a break in the curve 0 elongation as a function of the tension forces to which it is subjected. It is quite obvious that in the course of the operations on the thread, the latter must not be. subjected to forces which .tend to annul the desired effect. None of the operations, especially the drying, may be carried out under tension.

A certain number of patents describe the utilization of the swelling of the cellulose acetate for the purpose of facilitating the dyeing or the loadin or for obtainingmatt or woolly effects. %ut none of them has utilized the physical modification, produced in the thread of cellulose acetate by its swelling, for the purpose of rendering possible the very great twisting which is indispensable for obtaining .the effect of crepe.

To this end, the essential subject matter of the present application therefore consists in the utilization of this physical modification, which is made in the threads of cellulose acetate and which is preserved after the swelling agent has been removed and the threads have been dried and taken up their normal content of moisture, for the purpose of imparting to these threads the high deree of twist that the authors have found to be necessary for obtaining the effects called crepe in the fabrics.

According to the invention, a swelling bath is prepared such that the thread of cellulose acetate which is immersed therein undergoes, after drying, a shrinkage of about 10 to 15%, this shrinkage being due to the action of the swelling agent alone or to the combined action of the swelling agent and a colloid. The greater the shrinkage, the easier will it be to give the thread a high degree of twist but it will also be harder to obtain this shrinkage without decreasing the mechanical properties of the thread. On the other hand, the smaller the shrinkage, the harder it will be to twist the thread without diminishing its mechanical properties. There can be used as swelling agents all substances or mixturesof substances which are volatile or dissolved in a volatile solvent and which are capable of giving a thread of cellulose acetate immersed therein an increase of volume of at least 40 to 50%, for

example, sufiiciently concentrated aqueous solutions of alcohol or of organic acids, aqueous solutions of certain salts as sulphocyanides, methyl alcohol, benzine, or mixtures of these bodies, on condition that these mixtures are not solvents of cellulose acetate or that, on evaporation of the more volatile part of the mixture, a solvent of cellulose acetate does not remain on the thread, unless it can be removed by a suitable washing while preserving the physical modification made by the thread.

As colloids, there may be used substances such as gelatine, vegetable gums etc. and, in general, all substances that are soluble in the above mentioned liquids and are capable of increasing the shrinkage imparted to the thread of cellulose acetate by the swelling agent.

Moreover, the conditions of temperature, of duration of immersion, of concentration of the swelling agent and of the colloid may vary in accordance with the nature of the thread em loyed (titre, size of the fibres, origin), 0% the swelling agent and of the colloid. The threads of cellulose acetate thus subjected to the action of the swelling agent are then dried or washed with a suitable liquid according to whether it is more convenient to employ drying or washing for the purpose of removing the swelling agent. The latter having been removed, the dried threads, which preserve only their normal moisture content, can practically stand highdegrees of twist, for example 2900 to 3000 turns or more per metre for a thread with a titre of 100 deniers. The weaving of such hard twisted threads does not require any special precaution; they may be used alone or mixed with any other natural or artificial textiles, and the fabrics obtained after the usual treatments of degumming anddyeing present the characteristic 1 properties of crepesi. e., appearance, feel, firmness and elasticity.

There may be added to the swelling bath any lubricating product that can facilitate the manipulations of the thread.

Example I .5 litres of ethyl alcohol are added to a bath containing 200 grams 0 gel-atine dissolved in 5 litres of water. Cellulose acetate of 100 deniers is immersed therein at 45 C. After squeezing out and drying, the threads are given a twist of 3000 turns per metre, some being twisted to the left and others to the right. These threads are used for weaving at 27 picks per centimetre a warp of 45 threads per centimetre of cellulose acetate of 75 deniers, for example by two picks being twisted to the right and two picks being twisted to the left, the warp being run as in the case of taffeta, and there is thus obtained a fabric presenting, after scouring and dyeing, a shrinkage of about 1.5 to 20% in the direction of the weft and of iso 10% in the direction of the warp, and having the characteristic (ipalities of a good fabric called"crpe de G ine, an article that has never hitherto been really obtained by using solely threads of cellulose acetate.

Example H.Threads of cellulose acetate with a titre of 100 deniers are' immersed for minutes in a'swell' bath consisting of an aqueous solution of nitric acid conta' 32% of HNO and kept at a temperature 0 15 C, These threads are then washed with water until they no longer have an acid reaction. They are then dried and given a twist of 2900 turns per metre, some being turned to the left and others to the right.

These threads are used for weaving at 27 4 picks per centimetre a warp of threads per centimetre of cellulose acetate of 75 deniers, for example by two 'cks being twisted, t0 the right and twopicfis taffeta, and there is thus obtained a fabric present-ing, after scouting and d eing, a shrinkage of about 15 to 20% in the dlr tion of the weft and of 10% in the direction ualities of a good fabric called crepe de hine.

Example [lb-Threads of cellulose 'ace CLAUDE GLEMENCON.

being twisted to theleft, the warp being run as in the case of of the warp, and having the characteristic tate are immersed for 10 minutes in a swelling liquid consisting of a mixture of carbon tetrachloride and chloroform in the volumetric proportions of one part of carbon tetrachloride to three parts of chloroform and at a temperature of 15 to 17 (3., after which these threads are reduced by drying in a om rent ,of air at the ordinary temperature and, after taking up moisture, they are used as mdicated in-one of the two preceding examples.

What I claim and desire to secure by Letters Patent of the United States is 1. Process for the treatment of threads of cellulose acetate for use in the manufacture of fabrics with crepe effect-consisting in subjecting the threads before twisting a preliminary shrinkage by first subjecting them to the action of a swelling agent and then' eliminating said swelling agent and subsequently subjecting the shrunk threads to a twisting action of the order of 2800 to 3000 turns per metre for a thread of 100 denicrs.

2. Process for the treatment of threads of cellulose acetate for use in the manufacture I of fabrics with crepe eifect consisting in effecting a preliminary shrinkage in length of the untwisted threads of about 10 to 15% by'first subjecting them to a swelling agent to increase their volume by at least 40% and then eliminating theswelling agent, and subsequently subjecting the shrunk threads to a twisting action of the order of 2800 to 3000 turns per metre for a thread of 100 denicrs.

3. In the manufacture of crepe cfiect .5 fabrics fromcellulose acetate threads the 

